If your Outlook email suddenly stopped working today, you’re definitely not alone.
A widespread Microsoft 365 outage on November 12, 2026 is causing problems with Outlook, Exchange Online, Microsoft Teams and other Microsoft cloud services. Businesses across the United States and other regions have reported difficulty accessing email, connecting to Microsoft 365 applications and using collaboration tools.
Microsoft has acknowledged the problem and says its engineers are actively working to restore service.
For businesses that depend heavily on Microsoft 365, the outage is another reminder of just how much modern business operations rely on cloud services.
What Is Happening With Microsoft 365?
The problems initially appeared to center around Exchange Online, Microsoft’s cloud-based email platform behind Microsoft 365 business email.
Microsoft reported that users were having difficulty connecting to Exchange Online mailboxes through multiple connection methods.
These include:
- Outlook on the web
- Microsoft Outlook desktop applications
- Exchange ActiveSync used by mobile devices
- MAPI connections
- REST API connections used by applications and integrations
Microsoft is tracking the Exchange Online problem under incident EX1550543.
As the outage progressed, however, reports expanded beyond email.
Microsoft 365 users have also reported problems involving services including Microsoft Teams, SharePoint Online, Microsoft 365 Copilot and Microsoft Defender XDR. Microsoft said the disruption could affect service connectivity across multiple regions.
How Large Is the Microsoft 365 Outage?
The number of reports increased quickly.
At approximately 2:07 p.m. Eastern Time, Downdetector had recorded more than:
- 97,000 reports involving Outlook
- 38,000 reports involving Microsoft 365
- 4,500 reports involving Microsoft Teams
Downdetector numbers represent user-submitted reports rather than Microsoft’s actual customer count, so they shouldn’t be interpreted as the total number of affected users. However, they provide a good indication of how widespread the disruption has become.
Earlier in the outage, nearly 130,000 Outlook-related reports had been recorded shortly after 1 p.m. Eastern Time.
What Is Causing the Microsoft 365 Outage?
Microsoft’s investigation is still underway.
Early in the incident, Microsoft said portions of its infrastructure were experiencing elevated load, which appeared to be contributing to connectivity errors.
Microsoft later indicated that the elevated load was not simply the result of unusually high customer traffic. Instead, a large number of servers had unexpectedly become unavailable, causing additional traffic and workload to shift onto the remaining infrastructure.
Microsoft has been working to restore capacity while investigating why those servers became unavailable.
As part of its mitigation efforts, Microsoft says it has:
- Paused deployments and configuration changes
- Redirected traffic away from affected infrastructure
- Restarted affected servers
- Worked to safely return unavailable infrastructure to service
Microsoft described its response by saying it was aggressively pursuing multiple options to reduce the impact.
Is This a Cyberattack?
At this point, Microsoft has not announced that the outage is the result of a cyberattack.
Whenever a major cloud provider experiences an outage, speculation about DDoS attacks, ransomware or other security incidents tends to appear online fairly quickly.
There currently isn’t enough verified information to make that conclusion.
Until Microsoft publishes a confirmed root cause, businesses and IT administrators should avoid assuming the outage is security-related.
Why This Matters for Small Businesses
Microsoft 365 has become the central communications platform for millions of businesses.
A single Microsoft cloud disruption can potentially affect much more than someone’s ability to send an email.
Organizations may experience problems with:
Customer communications
If Exchange Online isn’t working, employees may be unable to send or receive customer emails.
Internal communication
Microsoft Teams may also experience connectivity or performance issues.
File access
Businesses using SharePoint Online for shared files, intranet sites or business processes could experience interruptions.
Microsoft 365 integrations
Third-party applications that connect to Microsoft 365 through APIs may also experience failures.
Reuters reported that the disruption was even affecting Microsoft 365 connectors used by AI providers including OpenAI and Anthropic.
This illustrates an increasingly important issue for businesses: cloud services are often interconnected.
An outage involving one major provider can sometimes affect multiple applications that depend on that provider behind the scenes.
What Should Microsoft 365 Administrators Do?
If users in your organization are reporting email or Microsoft 365 problems, don’t immediately assume the problem is with your firewall, Internet connection or individual computers.
Start by checking Microsoft’s service health information.
Microsoft 365 administrators can check:
Microsoft 365 Admin Center → Health → Service Health
Microsoft also publishes certain outage updates through the official Microsoft 365 Status account.
Administrators should document the symptoms users are experiencing and determine whether they match Microsoft’s reported incident before making major changes to their environment.
Avoid Making Unnecessary Changes
One of the biggest mistakes IT administrators can make during a major cloud outage is changing their environment while trying to fix something that is actually happening on Microsoft’s side.
For example, avoid unnecessarily changing:
- DNS records
- Exchange Online connectors
- Conditional Access policies
- Firewall rules
- Email authentication settings
- Outlook profiles
- Mobile device configurations
If the underlying issue is Microsoft’s infrastructure, these changes won’t fix the outage and could create additional problems once Microsoft restores service.
Instead, confirm Microsoft’s service status first.
What Should Businesses Tell Employees?
Communication becomes especially important when email itself is experiencing problems.
Organizations should have an alternative communication method available, such as:
- Microsoft Teams if it remains operational
- SMS messaging
- Internal messaging platforms
- Company emergency notification systems
- Phone trees or other predefined communication methods
IT teams should also remind employees that repeatedly restarting Outlook, recreating profiles or reinstalling Microsoft 365 applications is unlikely to resolve a Microsoft-side service outage.
Cloud Services Still Need a Business Continuity Plan
Microsoft 365 is generally extremely reliable, but no cloud service has 100 percent uptime.
Businesses should have basic contingency plans for situations where critical services such as email, collaboration platforms or cloud storage temporarily become unavailable.
That doesn’t necessarily mean maintaining an entirely separate email platform.
Instead, businesses should think about questions such as:
How would employees communicate if email stopped working for several hours?
Can employees still access important documents during a cloud outage?
Do customers have another way to contact the company?
Does IT have a way to communicate with employees outside Microsoft 365?
Even a simple outage communication plan can prevent confusion when a major service provider experiences problems.
Microsoft Continues Working on the Outage
As of November 12, 2026, Microsoft is continuing to investigate and mitigate the Microsoft 365 service disruption.
The company has been moving traffic away from affected infrastructure and restarting servers while investigating why a large number of systems unexpectedly became unavailable.
Because this remains an active incident, the exact scope, root cause and restoration timeline may continue to change.
Businesses experiencing problems should monitor the Microsoft 365 Service Health dashboard and Microsoft’s official status communications rather than making major changes to their Microsoft 365 environment.
Once Microsoft releases a final incident report, we should have a much clearer picture of exactly what caused today’s widespread Microsoft 365 outage.
